1. Field of the Invention
This invention relates to a circuit substrate and a circuit device and manufacturing process therefor. Especially, this invention relates to a circuit substrate and a circuit device on which plurality of circuit elements are mounted, and manufacturing process thereof.
2. Description of the Related Art
Previously, such method of separating each unit has been adopted: a conductive pattern which consists of a lot of units is formed on one large substrate, this conductive pattern is connected to circuit elements and, after that, each unit is separated (refer to the following patent document 1).
Referring to FIG. 10, previous circuit substrates and manufacturing method thereof will be described. FIG. 10(A), FIG. 10(B) and FIG. 10(C) are cross section view where each process is shown.
Firstly, referring to FIG. 10(A), a conductive pattern 104 which consists of a lot of units 106 are formed on the top surface of a substrate 100. The first groove 108 on the top surface and the second groove 110 on the back surface are formed on the border between each unit 106.
The average size of the substrate 100 is such that a lot of units 106 are formed on, for example, a substrate which consists of aluminum of about 1.5 mm thickness is applied. The top surface of such substrate 100 is covered with an insulating layer 102 that consists of the resin material with which filler is mixed.
On the top surface of the insulating layer 102, the conductive pattern formed in predetermined pattern by means of etching conductive film of a few tens of μm thickness. Here, the unit 106 is a unit element that consists of one circuit device, and same shape of conductive patterns 104 are formed on each unit 106. Plurality of units 106 are arranged in a grid on the substrate 100 though it is not shown in any figure here.
The first groove 108 is a groove formed on the top surface of the substrate 100 along with the border of each unit 106, and it has a cross section shape of V-type. Since the unit 106 is formed in a grid on the substrate 100, the first groove 108 provided between each unit 106 is formed in a grid. Here, when the thickness of the substrate 100 is 1.5 mm, the depth of the first groove 108 will be formed about 0.6 mm.
The second groove 110 is provided on the back surface of the substrate 100 corresponding to the place where the first groove 108 is formed. The width and the depth of the second groove 110 are formed same as the first groove 108.
Said first groove 108 and second groove 110 are formed by cutting the substrate 100 partially with the use of a cut saw rotating at high speed.
Next, referring to FIG. 10(B), circuit elements 112 are connected with the conductive pattern 104 of the each unit 106. Here, semiconductor elements such as transistor or IC and chip elements such as chip resistances and chip capacitors are shown as the circuit elements 112. The semiconductor element such as IC is connected with the conductive pattern 104 via thin metallic wire.
Then next, referring to FIG. 10(C), each unit 106 is cut off by dividing the substrate 100 at the place where the first groove 108 and the second groove 110 are provided. Because the thickness of the substrate 100 is locally thin in the area where the first groove 108 and the second groove 110 are provided, the substrate 100 can be easily separated in this area. There are some methods for dividing the substrate 100; for example, the substrate 100 is folded and divided in the area where both of the grooves are provided, then, diced, and so on.
After the above process of separation is completed, leads are bonded to pads which consist of the conductive pattern 104, the circuit element 112 and the substrate 100 are sealed with a use of sealing resin or casing material, then the circuit device is completed.
It is capable that many of circuit devices are efficiently manufactured by using the above mentioned method.
Next, referring to FIG. 11(A), the construction of the substrate 100 and the circuit device manufactured by the above mentioned manufacturing method will be described. First of all, the side surface of the substrate 100 made in the above mentioned manufacturing process has inclinations. Specifically, the side surface of the substrate 100 is composed of the first side surface 118 which is adjacent and inclined from the top surface and the second side 120 which is adjacent and inclined from the back surface. Here, the sizes of the first side surface 118 and the second side surface are equal. Moreover, the pad 116 that forms conducting pattern 104 like land is provided in the surrounding portion of the substrate 100, and the lead 114 is attached to the pad 116.
Moreover, the other methods have been proposed as methods of separating the substrate 100. For instance, refereeing to the patent document 2, the fact that it becomes easy to separate each metal substrate 2 from a metal substrate body 1 by separating the metal substrate 2 and creating the groove 3 which penetrates through the metal substrate body 1 is disclosed.
In addition, a printed circuit substrate dividing machine is disclosed in the patent document 3. Especially, it is disclosed that print circuit substrate 4 is separated by using rotary blades 31 and 32 in FIG. 1 of this document.
Moreover, referring to the patent document 4, the method of the separation of metal base print circuit substrate is disclosed. Especially, referring to the process chart shown in FIG. 1 of this document, firstly, a V-cutting groove 6 is created in the separation part a of the metal base circuit substrate 2 of which the top surface is covered by an insulating layer 3. Then, the metal base circuit substrate 2 is separated by adding the stress in the part where the V-cutting groove 6 was created after the insulating layer 3 upon the V-cutting groove 6 is removed by the laser.
Japanese Patent Publication Nos. 2003-318334, H7-142861, H6-79689 and H10-22630 describe the structures described above.
However, there was the problem that it is difficult for the structure of the substrate 100 shown in FIG. 11(A) to achieve both high-voltage and downsizing. Specifically, the sizes of the first side surface 118 and the second side surface 120 are in the same level as described above, and the width L 30 of the both surfaces is about 0.3 mm. In addition, it is necessary to place a certain distance between the edge part of the substrate 100 in which metallic material is exposed and the pad 116 in order to secure withstand voltage. For instance, the distance L 31 between them is about 0.5 mm. In addition, because the first side surface 118 and the second side surface 120 are inclined equally and protrude outside, the dimension of the substrate 100 becomes large and the downsizing of the entire device becomes difficult.
Referring to FIG. 11 (B), if the first grooves 108 which have equal depth are created in a grid on the substrate 100, there is a possibility of arising metallic burr at the part where the first grooves 108 intersect each other at a right angle. This metallic burr would be removed by means of spraying vapor or liquid in high pressure, however, it is difficult to remove all of the metallic burr. And if conductive metallic burr remains in the substrate 100, it drops on the substrate directly in the manufacturing process and picks up other metallic burr on a line, and it becomes attached to a circuit device as a product, and short-circuit might happen.
This invention is accomplished in view of the above mentioned problem and is directed to providing the circuit substrate and circuit device which achieve a good balances between withstanding high-voltage and downsizing and process method thereof.